Intel's Pentium 60 processor used a bus speed and processor speed of 60 MHz. All later processors have used multipliers to increase the internal clock speed while maintaining the same external clock speed, e.g. the Pentium 90 used a 1.5x multiplier. Modern Socket 370motherboards support multipliers from 4.5x to 8.0x, and FSB speeds from 50 MHz to a proposed 83 MHz standard. These higher speeds may cause problems with some PCI hardware.

Altering the FSB speed and the multiplier ratio are the two main ways of overclocking processors.